1. Field
Example embodiments relate to methods of forming a polymer-dispersed liquid crystal film, and more particularly, to methods of forming a polymer-dispersed liquid crystal film including dichroic dye.
2. Description of the Related Art
Polymer-dispersed liquid crystal (PDLC) display devices are devices in which light is scattered or transmitted by applying an electric field to the PDLC. The electric field allows for a change in the refractive indexes of a polymer and a liquid crystal uniformly mixed in a PDLC. In PDLC display devices, light is allowed to pass or is blocked by using only an electric field and not an orientation film or a polarizing plate. Also, a contrast of a display device may be improved by mixing a PDLC and dichroic dye. Generally, when dichroic dye is mixed with a liquid crystal, dichroic dye is inclined to be aligned in the same orientation as the liquid crystal. Thus, when dichroic dye is mixed with a PDLC, dichroic dye may be aligned or randomly distributed according to an orientation of liquid crystal included in the PDLC, thereby causing an optical change.
Conventionally, a PDLC film including dichroic dye is formed by injecting a mixed solution including a liquid crystal, a photo-polymerizable material, and dichroic dye between two substrates and exposing the mixed solution to ultraviolet (UV) rays, thereby curing the mixed solution. In this regard, the photo-polymerizable material refers to a material that is polymerized by photo-polymerization, and may be a monomer or an oligomer. Through the UV curing process, the liquid crystal is uniformly dispersed in the polymer, and dichroic dye may be uniformly present in the polymer and the liquid crystal. However, in a display device including a PDLC film formed by the method described above, dichroic dye present in the polymer may adversely affect optical characteristics of the display device. That is, dichroic dye present in the polymer may be immobilized by the UV curing process and the immobilized dichroic dye does not have an optical anisotropy. Thus, the dichroic dye adversely affects visibility of the display device. In addition, during the UV curing process, dichroic dye present in the polymer may continuously absorb UV rays to degrade UV curing characteristics.